1. Technical Field
The technical field relates to a printing method of a 3D printer, and specifically to a printing method for low melting-point material of a 3D printer.
2. Description of prior art
Recently, 3D printing technology develops very quick, and the price of a 3D printer becomes cheaper and cheaper. As a result, 3D models made by 3D printing technology are gradually popular around people.
Generally speaking, 3D printing technology in the related art usually adopts acrylonitrile-butadiene-styrene (ABS) resin as printing material. However, ABS resin will release poisonous gas during a printing procedure, and it does not smell good. As such, there are some new type 3D printers in the market adopt poly lactic acid (PLA) as the printing material. Comparing with ABS resin, PLA is environmental protection material made by corn, so it can decompose naturally, and it won't generate stink smell and release poisonous gas during the printing procedure.
Refers to FIG. 1 and FIG. 2, FIG. 1 is a schematic diagram of a model of related art, and FIG. 2 is a schematic diagram of a finished model of related art. Because the melting-point of PLA is low and PLA is soft, when printing a 3D model 2 by using PLA as the printing material, an ordinary 3D printer usually prints two layers of contour (basically an internal-contour 11 and an exterior-contour 12) of the 3D model 2. Therefore, the 3D printer can make sure that the finished 3D model 2 is strong enough.
A nozzle of the 3D printer is heated continually during the printing procedure, and PLA material won't be solidified immediately after being printed. As such, if the 3D printer prints the exterior-contour 12 at first and then prints the internal-contour 11 during the printing procedure, the finished exterior-contour 12 will receive heat from the nozzle continually when the 3D printer prints the internal-contour 11, and the exterior-contour 12 may be deformed because of the heat.
According to above descriptions, the 3D printer in the related art usually prints the internal-contour 11 at first and then prints the exterior-contour 12. Therefore, although the finished internal-contour 11 may be deformed when the 3D printer prints the exterior-contour 12, but it does not matter because the deformed internal-contour 11 does not affect an appearance of the finished 3D model 2.
Generally, the 3D model 2 is constructed by multiple printing-layers 1. The 3D printer first prints one of the printing-layers 1, then raises the nozzle to a printing position corresponding to the next printing-layer 1 (i.e., raising the nozzle to above the finished printing-layer 1) for printing the next printing-layer 1 thereof.
However, if the nozzle is raised directly from the finished exterior-contour 12, it still located in proximity of the finished exterior-contour 12. Therefore, the finished exterior-contour 12 may still be deformed by the heat of the nozzle if the nozzle stays in proximity of the finished exterior-contour 12 for excessively long time.
Besides, the melting-point of PLA is low, so drooling events may occur in the nozzle of the 3D printer adopting PLA. If the nozzle is raised directly from the finished exterior-contour 12, the drooling events may occur at the finished exterior-contour 12. Therefore, the finished exterior-contour 12 may be deformed by the heat of the drooled material.